1. Field of the Invention
This invention relates to the preparation of unsaturated aldehydes and specifically, to the preparation of the .alpha.- and .beta.-sinensals.
2. Description of the Prior Art
The .alpha.- and .beta.-sinensals are sesquiterpenic aldehydes which have been discovered in the oil of China orange (Citrus sinensis) [see J. Org. Chem. 30, 1690 (1965); Tetrahedron Letters 295 (1966)] and which owing to their organoleptic properties have a great value as flavouring agents for foods and beverages.
For the .alpha.-sinensal (Ia) and .beta.-sinensal (Ib) whose structure is derived from ocimene cis or trans and from myrcene (see formulae hereafter), the denomination .alpha. and .beta., respectively, has been adopted from analogy with the .alpha.- and .beta.-farnesenes. In the past, a reverse system has been used, .alpha. in place of .beta. and vice versa (see for instance the above references).
Until now the .alpha.- and .beta.-sinensals have not been prepared synthetically.